DIVISION AND CLASS I PICA TION. 1 3 1 



tion is, in a given case, the more &quot; natural,&quot; and will thus raise once more 

 the ultimate difficulty : How are we to judge and decide between conflict 

 ing &quot; resemblances &quot; or &quot; affinities &quot; in a case in which some individual 

 object resembles those of one group in the attributes #, , c, and those of 

 another group in the attributes d, e, /? Here is where our judgment, 

 as between the appearances, will be inevitably influenced by our own beliefs 

 and convictions, by our own views, theories and prepossessions, whether 

 these be helpful or the reverse towards an approximation to a true know 

 ledge of the things classified. How are we to decide whether, for this 

 purpose, a, b, c are more or less important than d, e, /? Will not our 

 decision depend upon what we regard as the most valuable kind of knowledge 

 about the things ? And if we take into account the second great fact referred 

 to above (67) : that naturalists claim to have detected evidences of the gradual 

 evolution of &quot; species &quot; from a few parent stems, evidences of the mutability 

 of &quot; species &quot; in living things : will we not regard as &quot; most important &quot; 

 grounds of classification the presence or absence of such attributes as would 

 seem however otherwise insignificant and likely to escape notice to point to 

 a common descent ? This is what has actually happened. The Evolution 

 hypothesis has determined scientists to regard affinity between species no 

 less than between individuals as indicative of a common original ancestry ; 

 to supplement the knowledge of actual living forms by the knowledge of 

 fossil remains ; to look for traces of the supposed transformation and 

 evolution of &quot; species &quot; in surviving fragments from bygone, prehistoric 

 ages ; to discard any more obvious and striking resemblances that may seem 

 to be merely i superficial and to have no close connexion with the origin and 

 descent of the living forms colour, for instance, in the case of flowers, as 

 of much less importance than other less obvious and less easily detected re 

 semblances as, for instance, in the structure of certain minute organs, 

 resemblances which, however hidden from view, point to identity of origin 

 to descent from a common stock. 



Although, under the influence of the evolution hypothesis, &quot; conceptions 

 of the nature and functions of classification [of plants and animals] naturally 

 underwent some alteration,&quot; yet &quot; as regards the details of actual classifica 

 tion very little change has been introduced &quot;.* The conception of any such 

 hypothesis, and its application to facts, invariably stimulates scientific 

 inquiry and leads to valuable results, and this even though the hypothesis 

 itself may turn out afterwards to have been partially or wholly erroneous. 2 

 It is not the function of logic, but of the respective sciences in which such 

 hypotheses are employed, to discuss the latter on their merits. The evolu 

 tion hypothesis has been mentioned here only on account of the bearing it 

 has on the interpretation and application of the general law which logic 

 seeks to formulate for &quot; natural classification &quot; or &quot; classification for general 

 purposes &quot; : that it must be carried out on the basis #/* IMPORTANT attributes. 



69. SCIENTIFIC NOMENCLATURE AND SCIENTIFIC TERMIN 

 OLOGY. To carry on successfully the work of classification, two 

 distinct systems of names or terms are indispensable : (a) a 



1 VENN, op. d/./p. 338. a C/. infra, bk. iv., ch. v. 



9* 



